1. Field of the Invention
The present invention relates to an object handling apparatus for handling an object such as a workpiece using a robot to transfer the object from one place to another place.
2. Description of Related Art
For automatically performing machining of workpieces, assembling of parts, etc., robots are used as means for transferring objects such as workpieces and parts from one process to the next process. In the case where the next process is machining of an object by a machine such as a machine tool, it is required that the object is precisely positioned to have a predetermined position/orientation so as to be mounted by an object mounting jig of the machine tool. Similarly, in the case of assembling of parts, it is required that the objects held by the robot is precisely positioned to have a predetermined position/orientation in transferring the object to the next process.
To meet the above requirements, conventionally, the objects are supplied by pallets having positioning devices such as positioning jigs for positioning the objects on the pallets so that the robot holds the objects having predetermined position/orientation. By supplying the objects positioned on the pallets by the positioning devices, the robot securely holds the object at a predetermined holding position/orientation taught in advance. However, there are problems that the pallets equipped with the positioning devices are of high price and a great number of pallets with different kinds of positioning devices have to be prepared for different kinds of objects.
Further, if the object is greatly displaced from the predetermined position/orientation on the pallet by an unexpected cause, the robot fails in holding the object by a robot hand to cause a stoppage of the automatic operation.
Even if the object is held by the robot hand, if position/orientation of the object held by robot hand relative to the robot hand is displaced from the predetermined position/orientation, there arise a problem in transferring the object to the next process. For example, in the case where the next process is machining of the object by the machine such as a machine tool, if there is a displacement of the position/orientation of the object relative to the robot hand, the object can not be mounted on the machine by the object mounting jig.
To cope with the above problem, various kinds of robot hands designed for various shapes and materials of the objects have been prepared so that the position/orientation of the object held by the robot hand relative to the robot hand is not displaced from the predetermined position/orientation. However, it is necessary to prepare a large number of robot hands designed for holding the various kinds of objects, and also rests for placing the large number of robot hands are necessary so that an installing area of the apparatus increases, to rise manufacturing cost of the apparatus and products.